The present invention relates to a digital X-ray photography device for taking an X-ray photograph by detecting X-rays which have been transmitted through a subject by radiating X-rays on to the subject while rotating an X-ray tube unit and an image detecting system around the subject on a table, and obtaining inspection images of a portion to be diagnosed of the subject, and relates more particularly to a digital X-ray photography device which can easily execute an inspection of the diagnosed portion of the subject by discriminating between a rotational stereoscopic photography and a tomography by one set of X-ray photography device.
According to the digital X-ray photography device of the present invention, it is possible to reduce time required for taking an X-ray photograph by rotating the X-ray tube unit and an image system unit for taking an X-ray photograph around a subject, and it is also possible to always observe the status of the subject.
According to a conventional digital X-ray photography device, within a gantry, installed on a floor surface, having an opening for inserting thereinto a table of a subject in a horizontal direction at about the center of a standing portion, the X-ray tube unit and the image detecting system are disposed face to face, in a one to one relationship, on a ring-shaped rotation supporting unit provided rotatably around the opening, with the rotation center of the rotation supporting unit sandwiched between the X-ray tube unit and the image detecting system. Further, two units have been structured independently as separate unites; an X-ray CT unit for obtaining two-dimensional tomograms which are sliced images of the diagnosed portion of the subject, photographed by rotating the rotation supporting unit around the subject, and an X-ray rotational stereoscopic photographing unit for observing the diagnosed portion as stereoscopic images by displaying the photographed images around the diagnosed portion as a dynamic picture.
Since the X-ray CT unit and the X-ray rotational stereoscopic photographing unit have been independently structured as separate units in the conventional digital X-ray photography device as described above, in the case of installing these two units in the same facility (such as a hospital), it has been necessary to have two independent photographing rooms equipped with X-ray shielding walls or it has been necessary to have a wide-spaced photographing room sufficiently wide enough to accommodate the two units with a common X-ray shielding wall provided in the room. Therefore, any one of the above alternative cases has required a wide space and costs for accommodating the two units, resulting in a costly arrangement.
Further, in the case of executing both the inspection by the X-ray rotational stereoscopic photographing unit and the inspection by the X-ray CT unit for a subject to be tested who requires an urgent diagnosis and treatment at a first aid and lifesaving facility or the like, for example, it has been necessary to carry the subject on a stretcher to a photographing room where one of the units is installed, move the subject to a table for the subject for this unit to carry out an inspection by an X-ray irradiation, then to place the subject on the stretcher to carry the subject to a photographing room where the other unit is installed, and move the subject to a table for the subject for this unit to carry out an X-ray irradiation. In this case, moving the subject between the photographing rooms and moving the subject from one table to the other forces a heavy load on the subject if the subject is in a seriously ill state, and accordingly it has been dangerous to move the subject. Further, in addition to the time required for actual inspections, it also takes time to carry the subject and move the subject between the tables of the respective units, and in order to carry out this operation in safe and in short time, many skilled operators and assistants have been required.
As examples of the conventional digital X-ray photography device, there are, for example, the Japanese Patent Unexamined Publication No. 2-156778 (a first prior art example) and the Japanese Patent Unexamined Publication No. 3-55040 (a second prior art example).
According to the above-described first and second conventional embodiments, in the case of carrying out a blood vessel fluoroscopic inspection, a rotation supporting unit is rotated around the subject and X-rays are simply radiated to the subject at the time of a forward rotation of the X-ray tube unit and the image system unit to take a photograph of the transmitted X-rays, then the X-ray tube unit and the image system unit are returned to an initial reference position by a backward rotation. Next, a contrast medium is injected into the subject by using a catheter and then the rotation supporting unit is started to take a photograph of the X-rays transmitted through the subject by the X-ray tube unit and the image system unit during a forward rotation this time after the contrast medium has been injected. Accordingly, it has been necessary to have a time for returning the X-ray tube unit and the image system unit to the initial reference position by a reverse rotation of these units. Thus, it has taken a long time to finish the whole photographing operation and therefore it has taken a long time for binding the subject, with a result of an increase in psychological burden on the subject in some cases. Further, during the period while the X-ray tube unit and the image system unit are being returned by a backward rotation, the transmitted X-ray image of the subject can not be obtained and operators such as radiologists can not observe the status of the subject, so that there has been an anxiety that this system can not meet a sudden change in the status of the subject.
Further, according to the first conventional example, two sets of television monitors are used as display units and two images having a predetermined phase difference, or a difference of rotation angle of the rotation supporting unit, obtained by an image picked up during the forward rotation are simultaneously displayed on the television monitors. Since an operator such as a radiologist watches this display with both eyes to have a stereoscopic view, it has not been possible for many people to simultaneously observe a stereoscopic image.
Further, according to the second conventional example, a so-called C arm or a U arm has been used as a rotation supporting unit, and the arm is exposed and the reproducibility of the position of the arm during a rotation has not been satisfactory, with a result that the rotation speed during a photographing period has been restricted to as low as 10 degrees per second, for example. Accordingly, time required for the whole photographing operation has been longer and an injection of the contrast medium into the subject has had to be for long time, with a result that pains are applied to the subject in some cases. Therefore, in order to reduce the photographing time, it has been necessary to take some actions such as to limit the range of an angle for taking an X-ray photograph of the subject, with a result that sufficient diagnosis information can not be obtained in some cases.